By Alan McCracken
The application techniques of pesticides has unfortunately not been developed to the same extent as the pesticides themselves. It is well known and recognized that pyrethroid insecticides work by contact and ingestion action and no vapor effect, which means that for good results they must be delivered to the target insect. The alternative is to obtain poor crop coverage and wait for the insects to find the chemical.
Firstly let us examine the reason for applying agrochemicals. The answer although obvious is not always understood; it is to protect the genetic potential of the crop being grown. For this reason the chemical products may be more correctly termed plant protection products and our objective should be to deliver the chemical product to the target insect or disease in the most efficient manner possible.
Modern agricultural aircraft can provide multiple services for the farmer including crop spraying, application of fertilizers and seeding in addition to other less well-known uses.
Corn and soybeans: Aircraft application can be of great value in enabling the application of insecticides and fungicides at the right time, unlike ground rigs that can be restricted because of wet soil conditions which means that the product is often applied too late, thereby being in-effective.
Citrus pests: Pests such as the Mediterranean fruit fly and the psyllids that transmit huanglongbing (HLB) can also be controlled using aircraft. This technique has been utilized successfully for several years now in Brazil; an initial test was made in Belize in August through a cooperative effort with AIRMAX. The technique was novel in that (1) low spray volume was used and (2) additives were used to enhance distribution of the droplets and protect the spray droplets from evaporation.
Sugarcane: Aircraft can be used to fertilize cane, apply ripening agents and to control outbreaks of “froghopper”.
Bananas: In most of the banana production areas in the world, growers are using outdated spraying techniques utilizing large quantities of oil as a tool for the control of black sigatoka which can be devastating to the crop if not controlled. We are now at the threshold of new technology utilizing high performance adjuvants with only a minimum of oil that achieves a double objective. These additives protect the spray droplets from evaporation but even more importantly provide excellent redistribution of the spray droplets on the leaves.
Locust control: For the control of swarms of locusts in Bolivia and Argentina agricultural aircraft are used to apply low spray volumes to not only kill the flying adults but also to spray a protective barrier ahead of the swarm to cut its progress and to save the crops.
Mosquito control: Several hundred aircraft and helicopters are in use every summer in the United States providing control of mosquitoes that are not only a nuisance for tourists but also transmit various diseases including West Nile virus and ZIKA.
In seeking to obtain increased spray coverage it is far more important and more economical to decrease the droplet size than to increase the spray volume. Many entomologists/agriculturalists have always thought that higher volumes mean better coverage; this is erroneous and has led to the following:
• Poorer coverage of crop and pests as large droplets fail to penetrate dense foliage often due to mechanical limitation in atomization.
• A slower rate of work by the equipment often resulting in missing the ideal moment for application and spraying being conducted under adverse weather conditions in order to cover the area.
• Major problems with soil contamination especially when farmers apply very high volumes of 10 gals/acre or even more as in the case of the citrus crop. When using high volumes with ground machines, tests have proven that a very high percentage of the chemical runs -off and results in severe soil contamination.
• An increase in application costs, yet a reduction in the quality of the application.
What are the advantages of lower spray volumes?
• The most important is probably that the chemical ingredient is more concentrated enabling higher efficacy, such that one spray droplet may be adequate to kill a particular insect.
• Higher productivity of the aircraft as less time is wasted refilling with water.
• Higher productivity in terms of acres covered; spraying can often be finished before mid-day when the weather is usually less-favorable.
• A much larger area per hour than ground machines under ideal spraying conditions.
Any questions or comments to: <firstname.lastname@example.org>
Editor’s Note: During the past 2 years Alan McCracken has been providing technical support to AIRMAX located at Spanish Lookout Airport. The objectives are to obtain better results with the chemical products and to improve the efficiency of operation with more precise control of all aspects of the application.